Various airbag systems are known in the art for inflating upon the impact of a moving vehicle to provide protection against injury of a passenger or occupant of the moving vehicle. Airbags can be placed in various places relative to an occupant of a vehicle to provide varying amounts of protection while minimizing the risk of injuring the occupant during the normal operation of the airbag. For example, airbags are commonly placed in the steering wheel or dashboard of an automobile such that when the automobile experiences a head on collision, the airbag will inflate to minimize the injury to a passenger occupying one of the front seats of the vehicle. The airbag, however, in operation, must inflate at a rapid rate of speed. Because the airbag is located opposite the passenger in the steering wheel or dashboard of the automobile, the airbag in operation expands toward the passenger, sometimes striking the passenger with an undesirable amount of force.
To minimize this undesirable airbag impact, various known airbag systems place the inflatable airbag in close proximity to the passenger such that in operation, the airbag will inflate away from the body of the occupant and still provide the desired injury protection as that of conventional steering wheel or dashboard based airbag systems. These known alternative airbag systems place the airbag in a variety of positions. For example, certain known systems provide for an airbag system independent of the vehicle. These systems, however, require the occupant to properly place and otherwise configure the airbag system on the seat belt, seat belt buckle, or other portion of the vehicle. It is desirable that passenger protection systems such as an airbag system be usable without affirmative occupant action or intervention beyond that normally required to secure the seat belt about the seat occupant to minimize the risk of mishandling by the occupant and to reduce the inconvenience of the occupant.
In other known airbag systems, the airbag is integrated with the seat belt or a portion thereof. The airbag portions of such systems, however, typically experience undesired wear because of the retraction of the airbag portion through guide loops and into retractors during normal use of the seat belt.
U.S. Pat. No. 6,419,264 discloses an airbag that is integrated with a shoulder belt portion of the seat belt. The shoulder belt airbag is too large to fit through the upper, guide loop, and even if it could it would not be able to be retracted onto the spool of the retractor in a practical way. Accordingly, systems like this generally necessitate the use of multiple retractors to provide some flexibility at least at the lap belt portion of the seat belt system. As is apparent, it would be desirable to reduce the number of retractors in a given seat belt system for cost reduction purposes.